title: PRK1 is targeted to endosomes by the small GTPase, RhoB.
abstract: RhoB has been shown to be an endosomal GTPase both by immunocytochemistry and electron microscopy, however, its role in endocytosis is unknown. Elucidation of the cellular roles of other members of this superfamily of signaling proteins has come with the identification of their downstream partners. We show here that the recently isolated serine/threonine kinase PRK1 is targeted to the endosomal compartment by RhoB. This is established both through immunofluorescence and cell fractionation. PRK1 is shown to interact with activated RhoB in cells and is localized to endosomes through its Rho-binding HR1 domain. Translocation of PRK1 to the endosomal compartment by RhoB is accompanied by a shift in the electrophoretic mobility of the kinase indicative of an accompanying activation.
authors.affiliation: Protein Phosphorylation Laboratory, Imperial Cancer Research Fund, 44 Lincoln's Inn Fields, London WC2A 3PX, United Kingdom. mellor@icrf.icnet.uk
authors.forename: H
authors.initials: H
authors.lastname: Mellor
authors.forename: P
authors.initials: P
authors.lastname: Flynn
authors.forename: C D
authors.initials: CD
authors.lastname: Nobes
authors.forename: A
authors.initials: A
authors.lastname: Hall
authors.forename: P J
authors.initials: PJ
authors.lastname: Parker
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001692:Biological Transport; D002451:Cell Compartmentation; D011992:Endosomes / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D020558:GTP Phosphohydrolases / Q000235:genetics / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D011233:Precipitin Tests; D011493:Protein Kinase C; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D017384:Sequence Deletion; D015398:Signal Transduction; D020743:rhoB GTP-Binding Protein
chemical_list: D008565:Membrane Proteins; D011994:Recombinant Proteins; C061570:protein kinase N; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins; D020743:rhoB GTP-Binding Protein